Managing routers and floating IPs
A router in OpenStack represents a virtual routing device that provides routing capabilities to directly connected networks. To provide end-to-end connectivity to a virtual machine, a router must be connected to an external provider network and the tenant network where the instance resides. Typically, routers are created and managed by individual projects. By default, external provider networks are shared and available for use by all projects. The following diagram represents an external provider network owned by the ADMIN
project and utilized by three other projects:
In Figure 4.2, three projects have routers connected to an external provider network. The external provider network not only provides connectivity to the routers and the networks behind them, but also provides a network from which floating IPs can be derived. Floating IPs provide 1-to-1 address translations that allow external clients to connect directly to instances.